Whereas the degree of invasion and metastases corresponds to prognosis in adults, this relationship is not seen in the pediatric population. In fact, the presence of lymph nodes does not affect the prognosis in children and adolescents. The reason for this is multifactorial and can be attributed to an overwhelming majority of well-differentiated cancers, low incidence of bone metastasis, and excellent response to RAI.
- Bone metastasis also has a low incidence in childhood thyroid cancers, occurring in less then 5% of patients.
- Individuals with radiation-induced thyroid cancer are at an increased risk for additional cancer later in life.
Pediatric patients have higher local and distant recurrence rates than adults, but they tend to respond rapidly to therapy. The prognosis is excellent in children, with mortality rates of less than 10%.
The overall 20-year survival rate is 92-100%.
Some studies report young age as the major determinant of recurrence in pediatric-differentiated thyroid carcinoma, which suggests a difference in tumor biology.
Rearrangements in the ret protooncogene have been observed in those exposed to radiation, with a reported ret rearrangement rate between 50 and 70%. Williams et al studied Chernobyl-induced thyroid tumor behavior and found that thyroid tumors associated with the ret and PTC3 oncogenes were more aggressive, faster growing, and less differentiated. Thyroid tumors with the ret/PTC1 oncogene had more benign characteristics and were slower growing.
Author: Mark E Gerber, MD, FACS, FAAP Clinical Assistant Professor of Otolaryngology, University of Chicago, Pritzker School of Medicine; Section Head, Pediatric Otolaryngology-Head and Neck Surgery, NorthShore University HealthSystem
Co-Author: Brian Kip Reilly, MD Assistant Professor of Otolaryngology and Pediatrics, Department of Otolaryngology, Children's National Medical Center, George Washington University School of Medicine